A human being is mostly in a normal gravity condition when the position of the heart is higher than the feet, no matter sitting or standing. In this condition, the blood circulation is similarly depending on the gravity. In a massage chair, considering the massage experience, a proposal is to dispose the backrest portion and the seat portion of the massage chair adjustable, so that the feet position can be higher than the heart when the human body keeps curved so that the blood circulation turns to a zero gravity or antigravity condition, so as to obtain a different massage effect. Tests show that it gets a different experience under zero gravity or antigravity condition and thus the human being gets well relax and feels comfortable.
Applied with above technology, there are leisure reclining chairs, for example in Chinese patent database with application number CN201020539131.4, disclosed is a backwardly reclined chair with a negative angle. The backwardly reclined chair is applied with a power push bar to revolve the backwardly reclined chair to a negative angle, so that the head position of the human body is lower than the position of the feet, blood flows to the head, so that the human being feels the head screwed on, and eliminates tiredness in a few minutes. This backwardly reclined chair with a negative angle comprises a seat structure and two leg assemblies, the seat structure comprises a seat portion and a calf stand, the seat portion is movably connected to the calf stand; below the seat structure, a power push bar with a switch button is fixedly attached to the leg assemblies, the head portion of the power push bar is connected to a connection point of seat structure hinge and the leg assemblies stand hinge; two sliding mechanisms are symmetrically disposed inside the chair leg assemblies; each sliding mechanism comprises a support brace fixedly disposed inside the leg assemblies, the bottom of the support brace is disposed with two spaced plane bearing rollers, two spaced concave positioning rollers are disposed above the internal side of the two plane bearing rollers; an arc brace runs through the two concave positioning rollers and the two plane bearing rollers, the rear end of the arc brace is disposed with a positioning block, the arc brace is disposed with several screws to fix to the seat structure. The measure is to disposed an arc rail convex downward below the chair, the arc rail slides between at least two fixed points, so that the whole backrest portion and seat portion slide along the travel of the arc rail to the fixed points, thus realizing a negative angle effect. This measure has obvious disadvantages: as the arc rail and the fixed points bear the whole weight of the chair and the user, it needs high cooperation precision, otherwise, the motion noise is large and the slide is bad due to deformation, burr or damage, resulting in a bad feeling, on the other hand, high cooperation precision calls for high quality of manufacturing of the motion components of the massage chairs, resulting in high costs.
Besides, for some wooden high-end leisure reclining chairs, the power push bar is usually assembled at the cross beam in the front to push the seat structure to slide on the seat frame, this structure of reclining chair needs a seat structure with high bearing stress, if the bearing stress is not even enough, when the power push bar pushes the human body to reposition to a normal sitting pose, a large counterforce on the wooden cross beam is generated thus to make the wooden cross beam broken, resulting in short service life; besides it is unsuitable for heavy users.